Migrate 'event' and 'expression'

chapters/equations.tex

@@ -572,6 +572,9 @@ \section{Synchronous Data-flow Principle and Single Assignment Rule}\label{synch
 
 \section{Events and Synchronization}\label{events-and-synchronization}
 
+An \firstuse{event}\index{event} is something that occurs instantaneously at a specific time or when a specific condition occurs.
+Events are for example defined by the condition occurring in a when-clause, if-clause, or if-expression.
+
 The integration is halted and an event occurs whenever an event
 generation expression, e.g.\ \lstinline!x > 2! o or \lstinline!floor(x)!, changes
 its value. An event generating expression has an internal buffer, and

chapters/glossary.tex

@@ -1,14 +1,5 @@
 \chapter{Glossary}\label{glossary}
 
-\glossaryitem{event}: something that occurs instantaneously at a specific time
-or when a specific condition occurs. Events are for example defined by
-the condition occurring in a when clause, if clause, or if expression.
-(See \cref{events-and-synchronization}.)
-
-\glossaryitem{expression}: a term built from operators, function references,
-components, or component references (referring to components) and
-literals. Each expression has a type and a variability. (See \cref{operators-and-expressions}.)
-
 \glossaryitem{flattening}: the computation that creates a flattened class of a
 given class, where all inheritance, modification, etc.\ has been
 performed and all names resolved, consisting of a flat set of equations,

chapters/operatorsandexpressions.tex

@@ -1,8 +1,8 @@
 \chapter{Operators and Expressions}\label{operators-and-expressions}
 
-The lexical units are combined to form even larger building blocks such
-as expressions according to the rules given by the expression part of
-the Modelica grammar in \cref{modelica-concrete-syntax}.
+The lexical units are combined to form even larger building blocks such as \firstuse{expressions}\index{expression} according to the rules given by the \lstinline[language=grammar]!expression! part of the Modelica grammar in \cref{modelica-concrete-syntax}.
+For example, they can be built from operators, function references, components, or component references (referring to components) and literals.
+Each expression has a type and a variability.
 
 This chapter describes the evaluation rules for expressions, the concept
 of expression variability, built-in mathematical operators and